ECE Regulation 48, Rev. 6 establish, for vehicles of categories O3 and O4, which are homologated after 18.10.2017, the sidemarker lamps must flash in the same phase and frequency as the corresponding direction indicators.
Random number of side markers may be connected to the cable of the output side, which will be centrally switched by the Blink Unit. The whole current consumption of the side markers may not exceed 1A!
The possibility to use this has existed since 1 October 2015.